Miniature microphones, such as those used in hearing aids, convert acoustical sound waves into an audio signal, which is processed (e.g., amplified) and sent to a receiver of the hearing aid. The receiver then converts the processed signal to acoustical sound waves that are broadcast towards the eardrum. In one typical microphone, a moveable diaphragm and a charged backplate convert the sound waves into the audio signal. The diaphragm divides the inner volume of the microphone into a front volume and a rear volume Sound waves enter the front volume of the microphone via a sound inlet.
Most prior art microphones, such as the prior art microphone of FIG. 1, have a sound inlet that includes a large inlet nozzle for receiving sound from the ambient environment. The large dimensions of the inlet nozzle can be a problem because hearing aids often have very limited space.
Further, the front volume and back volume within the microphone housing are typically of different sizes, causing the inlet nozzle, which is placed near the front volume, to be located asymmetrically on one of the exterior surfaces Mounting a microphone having an inlet nozzle asymmetrically located on its exterior surface can be problematic in some types of hearing aids because the inlet nozzle must be aligned with the hearing aid's opening to the ambient environment in the hearing aid while the microphone is positioned in a spatially constrained location.